#include <bits/stdc++.h>
using namespace std;
#define PI 3.1415926
#define   SQUARE(x) ((x)*(x))
//double SQUARE(double x) { return x*x;}

int main()
{
	int n, x,y;
	scanf("%d%d%d",  &n, &x, &y);
	n = n - ceil(y*1.0/x);
	if(n<=0)n=0;
  printf("%d", n);

  return 0;
}
